Disclosed herein is a toner comprising a colorant wax dispersion and a process for preparing a toner comprising using a single colorant wax dispersion rather than two separate dispersions comprising separate colorant dispersion and a separate wax dispersion.
Aqueous dispersions of dyes or aqueous dispersions of pigments can be dispersed to have an “average” particle or drop size D50 of less than about 150 nanometers and which are stabilized using a dispersant, plus other ingredients including lubricant, solvents and binders. “Average” particle or drop size is typically represented as D50 or d50, or defined as the volume median particle size value at the 50th percentile of the particle size distribution, wherein 50% of the particles in the distribution are greater than the d50 particle size value, and the other 50% of the particles in the distribution are less than the d50 value. Average particle size can be measured by methods that use light scattering technology to infer particle size, such as Dynamic Light Scattering. The particle diameter refers to the length of an individual drop of the discontinuous layer as derived from images of the particles generated by Transmission Electron Microscopy or from Dynamic Light Scattering measurements.
Pigments are typically heavier than water and tend to agglomerate and settle unless they are stabilized by a dispersant.
Numerous processes are within the purview of those skilled in the art for the preparation of toners. Emulsion aggregation (EA) is one such method. These toners are within the purview of those skilled in the art and toners may be formed by aggregating a colorant with a latex polymer formed by emulsion polymerization. For example, U.S. Pat. No. 5,853,943, the disclosure of which is hereby incorporated by reference in its entirety, is directed to a semi-continuous emulsion polymerization process for preparing a latex by first forming a seed polymer. Other examples of emulsion/aggregation/coalescing processes for the preparation of toners are illustrated in U.S. Pat. Nos. 5,403,693, 5,418,108, 5,364,729, and 5,346,797, the disclosures of each of which are hereby incorporated by reference in their entirety. Other processes are disclosed in U.S. Pat. Nos. 5,527,658, 5,585,215, 5,650,255, 5,650,256 and 5,501,935, the disclosures of each of which are hereby incorporated by reference in their entirety.
Toner systems normally fall into two classes: two component systems, in which the developer material includes magnetic carrier granules having toner particles adhering tribo electrically thereto; and single component systems (SDC), which may use only toner. Placing charge on the particles, to enable movement and development of images via electric fields, is most often accomplished with tribo electricity. Tribo electric charging may occur either by mixing the toner with larger carrier beads in a two component development system or by rubbing the toner between a blade and donor roll in a single component system.
Emulsion aggregation toners can be prepared using aqueous dispersions of pigments and aqueous dispersions of waxes. A typical wax loading for emulsion aggregations toners is about 7 weight percent wax based on the total weight of the toner composition. A typical pigment loading for emulsion aggregation toners is about 5.5 weight percent cyan pigment, or 9.0 weight percent magenta pigment, based on the total weight of the toner composition. Separate wax dispersions and separate pigment dispersions are prepared for use in preparing emulsion aggregation toners. The processing costs for preparing separate wax dispersions and separate pigment dispersions are major components of emulsion aggregation toner cost structure.
Hyper-pigmented emulsion aggregation toners are desirable. A hyper-pigmented emulsion aggregation toner has a smaller toner particle size than currently available emulsion aggregation toners. In order to achieve good print quality, such as good color gamut, smaller particle sized toners require higher pigment loading. Hyper-pigmented emulsion aggregation toners can require 1.4 times the amount of pigment as currently available emulsion aggregation toners. However, the amount of pigment which can be incorporated into hyper-pigmented toner compositions is limited. High pigment loaded toners may require coalescence time that is longer than current emulsion aggregation processes and therefore result in higher manufacturing cost.
Currently available toners and toner processes are suitable for their intended purposes. However a need remains for improved toners and toner processes including improved methods for producing toner, which decrease the production time and cost. Further, a need remains for improved toners and toner processes that enable smaller toner particle size, such as 3.8 micrometer D50 diameter, than currently available emulsion aggregation toners. Further, a need remains for improved toners and toner processes that provided enhanced print quality including improved color gamut. What is further needed is a toner and toner process that provides hyper-pigmented emulsion aggregation toner.
The appropriate components and process aspects of the each of the foregoing U. S. Patents and Patent Publications may be selected for the present disclosure in embodiments thereof. Further, throughout this application, various publications, patents, and published patent applications are referred to by an identifying citation. The disclosures of the publications, patents, and published patent applications referenced in this application are hereby incorporated by reference into the present disclosure to more fully describe the state of the art to which this invention pertains.